Sensor clusters, consisting of acceleration sensors and rotational speed sensors, have been used in automotive engineering for some time for applications, for example in electronic stability programs (ESP), in flashover recognition and prevention and for navigation. These sensor clusters generally contain one to two rotational speed sensors for determining the yaw rate (angular velocity about an axis vertical to the standing surface of the vehicle) or the roll rate (angular velocity about the longitudinal axis of the vehicle) and one to two acceleration sensors for determining the transverse or longitudinal acceleration of the vehicle.
In the meantime it has proven possible to produce rotational speed sensors at low cost with characteristics that are adequate for the automotive field based on MEMS technology (MEMS=Micro Electro Mechanical Systems), so that sensor clusters with at least three rotational speed sensors and at least three acceleration sensors are also feasible for mid-range automobiles without high additional costs. Sensor clusters of this type are also referred to as IMUs (Inertial Measurement Units). An IMU contains three rotational speed sensors and three acceleration sensors. The acceleration sensors are disposed in such a manner that they measure the components of the acceleration vector of a fixed point in the vehicle in the longitudinal direction and transverse direction of the vehicle and vertical to the standing surface of the vehicle. These directions are generally orthogonal to each other in pairs. The rotational speed sensors are disposed in such a manner that they measure the components of the vector of the current angular velocity of the vehicle in respect of the same three directions.
With regard to the central monitoring of the different electronic systems in the vehicle and possibilities for using fewer sensors, such sensor clusters, which make their data available to different systems in the vehicle, are of particular interest.
If all or some of the corresponding sensors in such a sensor cluster are not oriented in the desired directions (e.g. due to errors in the manufacturing process), these incorrect orientations can generally not be located without taking measurements within the cluster housing.